Circular #include in OpenQube

I’m getting the following warning (repeatedly) from the OpenQube snapshot in Avogadro master (using Clang):

/Users/ghutchis/Devel/avogadro/libavogadro/src/extensions/surfaces/openqube/atom.h:20: circular inclusion of /Users/ghutchis/Devel/avogadro/libavogadro/src/extensions/surfaces/openqube/molecule.h

And yes, each header includes the other. Is there some nice way of handling this? It’s not critical for 1.1.0, but as we point towards a stable 1.2 release, I think we need to remove as many common compiler warnings as possible.